Treatment of wool with isocyanates in the presence of gamma-butyrolactone



United States Patent 3,112,157 TREATMENT 0F WOGL WITH ISOCYANATES IN THEPRESENE 0F -BUTYRQLA CTONE Nathan H. Koenig, Berkeley, Calif., assignorto the United States of America as represented by the Secretary ofAgriculture No Drawing. Filed Feb. 6, 1962, Ser. No. 171,535 12 Claims.(6i. 8-128) (Granted under Title 35, US. Code (1952), see. 266) Anon-exclusive, irrevocable, royalty-free license in the invention hereindescribed, throughout the world for all purposes of the United StatesGovernment, with the power to grant sublicenses for such purposes, ishereby granted to the Government of the United States of America.

This invention relates broadly to the chemical modification of wool byreacting it with an organic isocyanate. In particular, the inventionconcerns and has as its prime object the provision of processes whereinthe reaction of wool with organic isocyanates is conducted in thepresence of 'y-butyrolactone whereby to facilitate and promote the saidreaction. Further objects and advantages of the invention will beapparent from the following description wherein parts and percentagesare by weight, unless otherwise specified.

Prior to this invention it has been advocated that wool be modifiedbyapplying an organic isocyanate to the wool, followed by baking theisocyanate-impregnated wool in an oven. In another technique, the W001is heated with a solution of an organic isocyanate in an organic solventsuch as benzene or carbon tetrachloride. Under these conditions only aminor amount of the isocyanate actually reacts with the wool so that thedegree of modification is low.

In accordance with the present invention, wool is reacted with anorganic isocyanate in the presence of v-butyrolactone. The lattercompound catalyzes the actual chemical combination of the wool and theiso cyanate reactant. As a result, one is enabled to readily preparewools containing substantial proportions of combined isocyanate andhaving correspondingly improved properties. The modified wool productsso prepared exhibit increased resistance to acids, alkalis, and otherreagents which degrade normal wool.

'y Butyrolactone exhibits certain characteristics which favor its use asa catalyst for the reaction in question. Among these are a high boilingpoint (204 C.), a low vapor pressure, and a low order of toxicity. Thehigh boiling point of the compound is advantageous in that thewool-isocyanate reaction can be conducted at high tem peratures withoutrequiring pressure-tight vessels or other special appaiat-us. The lowvapor pressure of the compound is advantageous in reducing fire hazard.Further, -butyrolactone is a stable compound and does not react to anymaterial extent with wool. In sum, the characteristics ofv-butyrolactone indicate that it is a very useful catalyst for themodification of wool with isocyanates.

The unusual and effective action of y-butyrolactone as a catalyst forthe reaction of isocyanates with wool is exemplified by the followingcomparative tests: (a) dry Wool (1.2 g.) and phenyl isocyanate (6 ml.)were heated at 125 C. for 30 minutes. The wool was extracted withacetone and ethanol to remove unreacted reagents and dried. It was foundthat the increase in weight of the wool was only 4%; (b) dry wool (1.2g.) and 'y-butyrolaotone ml.) were heated at 125 C. for 2 hours. Thewool was extracted as described above and dried. The increase in weightof the wool was only 3%; (0) dry wool (1.2 g.) was heated with phenylisocyanate 2 ml.) and 'y-butyrolactone (4 ml.) at 125 C. for 30 minutes.

Patented Nov. 26, 1963 The wool was extracted as described above anddried. In this case, the increase in weight of the wool, due to reactionwith the isocyanate, was 37%.

The fact that -butyrolactone acts as a catalyst rather than a meresolvent is demonstrated by the following experimental data: Dry wool(1.2 g.), phenyl isocyanate (2 ml.), and 7-b11tYI'0121Ct0I16 (4 ml.)were heated for 60 minutes at 115 C. The wool was extracted with acetoneand ethanol to remove unreacted reagents and dried. It was found thatthe increase in weight of the wool, due to reaction with the isocyanate,was 31%. A series of experiments were then carried out under the samecondi tions but substituting for the v-butyrolactone the same volume ofthe following solvents: butyl acetate, bu-tyl ether, and xylene. Inthese runs, the increase in weight of the wool was only 2%.

Carrying out the process of the invention essentially involvescontacting wool with an isocyanate in the presence of 'y-butyrolactone.The reaction conditions such as proportion of reagents, specificisocyanate used, time, temperature, etc., are not critical but may bevaried to suit individual circumstances without changing the basicnature of the invention. The proportion of 'y-butyrolactone may bevaried widely and may be as low as 0.1 volume per volume of isocyanate.In the case of isocyanates which are normally solid, the volumeconsidered is that of the molten (liquefied) compound. Usually, it ispreferred to use a larger proportion of 'y-butyrolactone, i.e., about0.5 to 5' volumes thereof per volume of isocyanate, to attain anincreased reaction-promoting effect. The temperature of reaction may beabout from 25 to 140 C. The reaction rate is increased with increasingtemper-ature and a preferred temperature range to expedite the reactionwithout damage to the wool is 110-130 C.

It is preferred to carry out the reaction under anhydrous will beaccompanied by formation of insoluble isocyanate reaction products whichdeposit on the wool fibers. The

degree of modification of the wool is influenced by the proportion ofisocyanate taken up by the fiber, that is, the higher the uptake ofisocyanate the greater will be the modification of the wool. In general,the uptake of 'isocyanate may be varied about from 1 to 70%, by

weight. In conducting the reaction, the isocyanate reactant is generallyemployed in excess over the amount desired to be taken up by the fiber.The time of reaction will vary depending on the proportion of-butyrolactone, temperature of reaction, reactivity of the isocyanateselected, and the degree of modification desired. In general, thereaction may take anywhere from a few minutes to several hours.

The process in accordance with the invention may be carried out invarious ways. For example, the wool may be directly contacted with the'y-butyrolactone and iso cyanate reactant and the reaction mixturepreferably heated as indicated above to cause the isocyanate to reactwith the wool. In the alternative, the wool may be pretreated withy-butyrolactone and the isocyanate then added to the mixture and thereaction carried out as previously described.

' After reaction of the wool with the isocyanate, the chemicallymodified wool is preferably treated to remove excess isocyanate,-y-butyrolaotone, and solvent, if such is used. Thus, the wool may betreated as by wringing, passage through squeeze-rolls, centrifugation,or the like, to remove the excess materials. In place of such mechanicalaction, or following it, the product may be extracted with a solventsuch as trichloroethylene, benzene, acetone, carbon tetrachloride, etc.Successive extractions with different solvents may be used to ensurecomplete removal of all unreacted materials. The treated wool is thendried in the usual way.

By treating Wool with the isocyanate reagent as above described, thewool is chemically modified because there is a chemical reaction betweenthe isocyanate and the protein molecules of the wool fibers. As aresult, the modified wool exhibits many advantageous properties overnormal wool. Outstanding in this regard is the resistance of themodified wool to acids and alkalis as indicated by its decreasedsolubility in these reagents. This factor enables the modified wool tobe useful in applications where the products comes into contact withalkaline or acidic materials. In addition, the chemically modified wooldisplays a drastically decreased tendency to shrink when subjected tolaundering operations. The modified Wool is also much more resistant tooxidizing agents, which may be employed during bleaching or otherfinishing processes, as illustrated by its lowered solubility in theperacetic acid-ammonia test described later. Although the properties ofthe chemically modified wool indicate beyond question that actualcombination between the wool and the isocyanate has taken place, it isnot known for certain how the wool and isocyanate moieties are joined.It is believed, however, that the isocyanates react with all the siteson the wool molecule where there are reactive hydrogen atomstheseinclude such groups as amino, hydroxyl, thiol, phenolic, amide,guanidino, imidazoyl, and carboxyl. When the reagent is a diisocyanate,it is believed that cross-linking also occurs, that is, proteinmolecules are joined to one another through the diisocyanate. It is tobe particularly noted that the reaction in accordance with the inventiondoes not impair the wool fiber for its intended purpose, that is, forproducing woven or knitted textiles, garments, etc. Thus, at low andmoderate isocyanate uptakes, the chemical resistance of wool can begreatly improved without appreciably adversely affecting the tensilestrength, hand, or color of the wool.

The process of the invention may be applied to wool in the form offibers, as such, or in the form of threads, yarns, slivers, knitted orwoven goods, felts, etc.

The catalytic ability of 'y-butyrolactone is not restricted to anyparticular isocyanate or class of isocyanates. Consequently, theinvention may be applied in the reaction of wool with all types oforganic isocyanates. Particularly preferred are the aliphatic, aromatic,or aromatic-aliphatic compounds containing one or more isocyanategroups. These compounds may be hydrocarbon isocyanates or may containsubstituents on the hydrocarbon residue such as halogen (chlorine,bromine, iodine, and fluorine), ether groups, ester groups, nitrogroups, etc. Examples of compounds coming into the purview of theinvention are listed below by way of illustration and not limitation:

Typical examples of compounds in the category of aliphatic isocyanatesare methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropylisocyanate, butyl (normal, iso, secondary, or tertiary) isocyanate, amylisocyanate, isoamyl isocyanate, hexyl isocyanate, octyl isocyanate,2-ethylhexyl isocyanate, decyl isocyanate, dodecyl isocyanate,tetradecyl isocyanate, hexadecyl isocyanate, octadecyl isocyanate,cyclohexyl isocyanate, methyl cyclohexyl isocyanate, Z-chloroethylisocyanate, 2-bromoethyl isocyanate, Z-iodoethyl isocyanate,2-fiuoroethy-l isocyanate, 12-chlorododecyl isocyanate,4-chlorocyclohexyl isocyanate, Z-methoxy ethyl isocyanate, 2-ethoxyethyl isocyanate, Z-butoxy ethyl isocyanate, carbethoxymethylisocyanate, ethylene diisocyanate, propylene diisocyanate, butylenediisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate,hexamethylene diisocyanate, octamethylene diisocyanate, decamethylenediisocyanate, cyclohexylene diisocyanate, bis (2-isocyanatoethyl) ether,his

CH3 CIT;

3,5,3,5-bixylylene-4,4'-diisocyanate, i.e.,

1 R o o N- NC o it it (R is --CH3) diphenylmethane-4,4'-diisocyanate,i.e.,

biphenylene-4,4'diisocyanate, 3,3dimethoxy-biphenylene-4,4-diisocyanate, naphthalene, diisocyanatcs,polymethylene polyphenyl isocyanates, etc.

Typical examples of aromatic-aliphatic isocyanates are benzylisocyanate, chlorobenzyl isocyanates, methylbcnzyl isocyanates,methoxybenzyl isocyanates, nitrobenzyl isocyanates, Z-phenoxyethylisocyanate, 2-benzoxyethyl isocyanate, etc.

EXAMPLES The invention is demonstrated by the following illustrativeexamples:

Example I A series of runs was carried out wherein dry wool flannel wasreacted with monoisocyanates and diisccyanates in the presence of'y-butyrolactone. In these runs, the weight of dry Wool was 1.2 grams,the volume of isocyamate with 2 ml., the volume of vbutyrolactone was 4ml., and the temperature of the reaction was 125 C. The isocyanates, thereaction times, and the uptake of isocyanate are tabulated below.

Reaction Uptake of Isocyanate Time, isocyanate,

min. percent m-Tolyl isocyanate 00 37 o-Chlorophenyl isocyanate (50 432,5-Dichlorophenyl isocyanate. 90 61 p-Brornophenyl isocyanate 57o-Nitrophenyl isocyanate 00 51 Octadecyl isocyanate 120 18 35,3,5-Bixylylene-4,4-cliisoeyanatc. 120 12 Ilexamethylene diisocyanatc120 19 Example II The acid solubility of modified wools produced inaccordance with the invention and that of untreated wool were determinedin the following way: The wool sample is immersed in 5 N hydrochloricacid for one hour at 65 C. The loss in weight of the sample is thendetermined after thoroughly washing the acid-soaked wool. e increasedresistance of modified wools to hot hydrochloric acid is illustrated bythe following data:

sistance of the modified wools to the action of alkali by measuringtheir solubility in aqueous sodium hydroxide. In this experiment themodified wool sample was immersed in 0.1 N sodium hydroxide solution forone hour at 65 C. The loss in weight was determined after a thoroughwashing of the alkali-soaked wool with water. The results obtained aregiven below.

Uptake of Alkali Isocyanate isocyanate Solubility,

by wool, percent percent None (untreated wool) 0 13 Phenyl isocyanate 359 p-Bromophenyl isoeyanate 57 3 'I0lylene-2-4-(liisoeyanate 73,5,3,5-13iXylylene-4,4-diisocyanate 10 8 Hexarnetlrylene diisocyanate19 5 Example IV Experiments were carried out to determine the resistanceof the modified wools to oxidizing conditions by measuring theirsolubility in peracetic acid-ammonia. In this test, about 0.4 g. of woolis treated at room temperature for 24 hours with 100 ml. of 2% peraceticacid and finally for 24 hours with 100 ml. of 0.3% ammonium hydroxide.The loss in weight is determined after thorough washing with water. Theresults obtained are given be- 6 Example V Tests were carried out todetermine the improvement in shrinkage characteristics of the modifiedwools. The shrinkage tests were carried out as follows: The wool sampleswere milled at 1700 rpm. for 2 minutes at 4042 C. in an Accclerotor with0.9% sodium oleate solution, using a liquor to wool ratio of to 1. Afterthis washing operation, the samples were measured to determine theirarea. The improvement in shrinkage properties of wool modified inaccordance with the invention is demonstrated by the following data:

Uptake of Area Isocyanate isocyanate, Shrinkage,

percent percent None (untreated Wool) 0 42 Ihenyl isocyanate ll 7In-Tolyl iso cyanate 23 3 3,5,3,5-Bixylylene4,4-diisocyanate 10 7 Havingthus described the invention, what is claimed is:

1. A process for chemically modifying wool which comprises reacting woolunder essentially anhydrous conditions, in the presence of-butyrolactone, with an organic isocyanate of the class consisting ofaliphatic, aromatic, and aromatic-aliphatic isocyanates.

2. The process of claim 1 wherein the organic isocyanate is an arylisocyanate.

3. The process of claim 1 wherein the organic isocyanate is phenylisocyanate.

4. The process of claim 1 wherein the organic isocyanate iso-chlorophenyl isocyanate.

5. The process of claim 1 wherein the organic isocyanate is m-tolylisocyanate.

6. The process of claim 1 wherein the organic isocyanate is2,5-dichlorophenyl isocyanate.

7. The process of claim 1 wherein the organic isocyanate isp-bromophenyl isocyanate.

8. The process of claim 1 wherein the organic isocyanate is tolylenediisocyanate.

9. The process of claim 1 wherein the organic isocyanate is 3,5 ,3,5'-bixylylene-4,4'-diisocyanate.

10. The process of claim 1 wherein the organic isocyanate is analiphatic isocyanate.

11. The process of claim 1 wherein the organic isocyanate is octadecylisocyanate.

12. The process of claim '1 wherein the organic isocyanate ishexamethylene diisocyanate.

References Cited in the file of this patent UNITED STATES PATENTS

1. A PROCESS FOR CHEMICALLY MODIFYING WOOL WHICH COMPRISES REACTING WOOLUNDER ESSENTIALLY ANHYDROUS CONDITIONS, IN THE PRESENCE OF$-BUTYROLACTONE, WITH AN ORGANIC ISOCYANATE OF THE CLASS CONSISTING OFALIPHATIC, AROMATIC, AND AROMATIC-ALIPHATIC ISOCYANATES.